Still stuck on diffrential equations

In summary, the conversation is about expanding dx and dy in terms of du and dv, and finding an integrating factor 'mu' in terms of u and v to make 'mu'w exact. The final solution involves substituting x and y for u and v and rearranging to get 'mu'.
  • #1
sara_87
763
0

Homework Statement



let x + y = u and y = uv
Expand dx and dy in terms of du and dv

Homework Equations





The Attempt at a Solution



i got this answer:

dy = udv + vdu

and

dx = du - udv - vdu


is this correct?
 
Physics news on Phys.org
  • #2
Looks correct to me. Using the product rule on "y = uv", you get dy, and then a simple substitution in the equation "x + y = u" gives you dx. You got it.
 
  • #3
ok thanx
now that makes things harder

we have w=(1 - y e^(y/x+y))dx + (1 + xe^(y/x+y)dy

find an integrating factor 'mu' in terms of u and v such that 'mu'w is exact

after subing that lot in for x and y and dx and dy, and rearranging a little i got this:


'mu' = [ (1+u(1-v)d'mu' ... something long and horrible!

how do i do this?
 

Related to Still stuck on diffrential equations

1. What are differential equations?

Differential equations are mathematical equations that describe the relationship between a function and its derivatives. They are commonly used to model physical systems in various fields of science, such as physics, engineering, and biology.

2. Why are differential equations important?

Differential equations are important because they provide a powerful tool for understanding and predicting the behavior of complex systems. They allow us to mathematically describe the relationships between variables and their rates of change, which is crucial for making accurate predictions and solving real-world problems.

3. What are some common applications of differential equations?

Differential equations can be applied to a wide range of phenomena, including motion, heat transfer, population dynamics, electrical circuits, chemical reactions, and many others. They are used extensively in fields such as physics, engineering, economics, and biology.

4. How do you solve differential equations?

There are various methods for solving differential equations, including separation of variables, integrating factors, and power series. The specific method used depends on the type of differential equation and its initial conditions. In some cases, differential equations may also be solved numerically using advanced computational techniques.

5. What are the challenges of working with differential equations?

One of the main challenges of working with differential equations is that they can be difficult to solve analytically, especially for complex systems. Additionally, the accuracy of solutions depends heavily on the initial conditions and the assumptions made in the modeling process. Another challenge is ensuring the mathematical validity of the solutions, as small errors can lead to significant discrepancies in the results.

Similar threads

  • Calculus and Beyond Homework Help
Replies
19
Views
820
  • Calculus and Beyond Homework Help
Replies
7
Views
2K
  • Calculus and Beyond Homework Help
Replies
6
Views
758
  • Calculus and Beyond Homework Help
Replies
12
Views
1K
Replies
2
Views
1K
  • Calculus and Beyond Homework Help
Replies
11
Views
848
  • Calculus and Beyond Homework Help
Replies
5
Views
668
  • Calculus and Beyond Homework Help
Replies
13
Views
2K
  • Calculus and Beyond Homework Help
Replies
5
Views
1K
  • Calculus and Beyond Homework Help
Replies
20
Views
1K
Back
Top